The present invention relates to a measuring system for an engine of a vehicle, and more particularly, to system and method for measuring interference between an intake/exhaust valve and a piston.
Generally, an engine for generating drive power of a vehicle includes a piston, undergoing rectilinear movement inside a cylinder, and an intake valve and exhaust valve provided in a cylinder head. A connecting rod is attached at one and to the piston and at another end to an offset portion of a crankshaft such that the force of the piston is transferred to the crankshaft to rotate the same, thereby converting the reciprocating motion of the piston to rotary motion of the crankshaft.
The crankshaft outputs rotational power to a transmission in accordance with a clutch operation and rotates a camshaft through a timing belt. The intake and exhaust valves are opened and closed by the rotating camshaft to supply fuel and exhaust combustion gas.
The camshaft is driven at one-half the speed of the crankshaft, the camshaft and crankshaft being connected by the timing belt.
Each of the above elements of the engine has its own inherent rigidity and can experience distortion from a variety of factors including inertia, and load and torque from power transmission. With regard to the camshaft, as one end in rotatably supported while another end receives rotational force, load distribution in an axial direction along the camshaft is not even such that the same can become twisted.
Such distortion of the camshaft changes both the duration of opening and stroke of the intake and exhaust valves such that interference between the valves and piston results, a main cause of engine trouble.
As there is no prior art which precisely measures such distortion of the elements of the engine including the camshaft, it is difficult to obtain data to correct the problem of interference between the exhaust and intake valves and piston by making adjustments.
The object of the present invention is to provide a method and system for measuring interference between an intake/exhaust valve and a piston in which a torque value, causing distortion of rotating shafts; torsional deviation, generated when torque is transmitted to each rotating shaft, of each shaft; and rotational vibration, generated by distortion of each shaft and tension and rigidity of a timing belt are measured to calculate interference between the intake/exhaust valve and the piston such that the problem of interference can be rectified in the designing process.
To achieve the above object, the present invention provides a method for measuring interference between a valve and a piston, comprising the steps of measuring a standard torque value, related to camshaft distortion caused by engine RPM, through voltage detecting means; measuring torsional distortion deviation of a crankshaft and an injection pump shaft by fixing the camshaft and forcibly rotating the crankshaft by said standard torque value; measuring vibration generated when the camshaft, the crankshaft, and the injection pump shaft are rotated, and measuring a crankshaft rotational angle to detect a piston TDC position, both measurements being conducted at a predetermined level of engine RPM; displaying piston and intake/exhaust valve movement on a graph at the piston TDC position after analyzing torsional distortion deviation and vibration of each shaft; and determining whether there is interference between the intake/exhaust valve and the piston by comparing design values with that displayed on the graph.
The voltage detecting means is comprised of a strain gauge.
The strain gauge is provided on the camshaft at locations where distortion from power transmission is most severe.
The torsional distortion deviation is derived from measuring a distortion angle through use of protractors provided on sprockets of the crankshaft and the injection pump shaft.
The torsional distortion deviation is derived from measuring the torsional distortion deviation of the crankshaft by fixing the injection pump shaft and forcibly rotating the crankshaft.
The measuring of vibration is performed using a torsional vibration meter.
A system for measuring interference between a valve and a piston including first angle detecting means for detecting a rotating angle of a crankshaft; and second angle detecting means for detecting a rotating angle of an injection pump shaft, whereby the first and second angle detecting means measure torsional distortion deviation of a crankshaft and an injection pump shaft when torque, equaling camshaft distortion torque measured with the camshaft in a fixed state, is given either to the crankshaft or the injection pump shaft, the system being applied to an engine where the crankshaft, injection pump shaft, and the camshaft are connected through power transmission means.
The measurement of the camshaft distortion torque is measured by strain gauges provided at location on the camshaft where distortion, caused by torque from power transmission, is most severe.
The strain gauge comprises four resistors connected to each other through a Wheatstone bridge having first and second output terminals, and the system further comprising a first signal processor for processing signals output from the first output terminal of the Wheatstone bridge; a second signal processor for processing signals output from the second output terminal of the Wheatstone bridge; and a controller for analyzing signals from the first and second output terminals to determine camshaft distortion, and calculating standard torque from the determined camshaft distortion value and outputting the same.
A system for measuring interference between a valve and a piston, comprising reflective tape adhered to an outside circumference of sprockets of each shaft, the reflective tape made of material to enable the reflection of light; torsional vibration detecting means for emitting light toward each sprocket of each rotating shaft, receiving the reflection of this light, reflected by the reflective tape, and for outputting vibration of each shaft as an AC component signal; amplifying means for amplifying said output AC component signal; crankshaft angle detecting means for detecting crankshaft rotational angle from the crankshaft sprocket; recording means for storing, in a predetermined format, piston position information and AC component signals related to the vibration of each shaft; and waveform display means for graphically displaying said information of piston position and AC component signal relating to vibration of each shaft.
The crankshaft angle detecting means performs a photo interrupting process on gear teeth of the crankshaft sprocket.